A two-stroke engine is an internal combustion engine that completes a power cycle with a single complete rotation of a crankshaft and two strokes of a piston connected to the crankshaft. The strokes are typically denoted as compression and power strokes. One example of a two-stroke cycle engine is an opposed-piston engine in which two pistons are disposed in a bore of a cylinder for reciprocating movement in opposing directions along a central axis of the cylinder.
In operation, internal combustion engines, such as opposed-piston engines, discharge heat energy into the external environment through exhaust gas, engine cooling systems, charge air cooling systems, etc. The discharged heat energy that is not used to perform useful work is typically known as “waste heat.” Waste heat recovery (“WHR”) systems capture a portion of the waste heat to perform useful work, such as generating electrical energy via an expander (e.g., a turbine). Some WHR systems utilize a Rankine cycle (“RC”). The RC is a thermodynamic process in which heat is transferred to a working fluid in an RC circuit. The working fluid is pumped to a boiler where it is vaporized. The vapor is passed through an expander and then through a condenser, where the vapor is condensed back to a fluid. The expander may drive a generator to generate electrical energy. An Organic Rankine cycle (“ORC”) is an RC in which the working fluid is an organic, high molecular mass fluid with a liquid-vapor phase change at a lower temperature than that of water. Such a fluid enables heat recovery from relatively lower temperature sources relative to other RC systems.